The invention relates to the field of well drilling and discloses application of an organic amine salt of a structure of a formula (I) shown in the specification in the field of well drilling. In theformula (I), R1 is hydrogen o C1-C8 alkyl; R2, R3, R4 and R5 are identical or different and are respectively independently selected from hydrogen and C1-C8 alkyl; A- is a halide ion or an acid radicalion; and preferably A- is selected from at least one of citrate, acetate, oxalate and tartrate. By adopting the organic amine salt, later hydration dispersion of bentonite can be inhibited, meanwhilea viscosity reducing effect can be achieved, and the flow pattern of a high bentonite content fresh water type drilling fluid can be effectively adjusted.